Typically, tire building drums have a cylindrical body that is rotatable about its axis, and tire carcasses are assembled on this cylindrical body. Once a carcass has been assembled on the body, it is collapsed to facilitate removal of the assembled tire carcass and, for this purpose, the cylindrical body is constructed of a plurality of segments that will collapse inwardly from an extended position to a retracted position. The preferred form of a tire building drum includes radially collapsing segments. These segments are supported on radially extending slide mechanisms, and during the collapsing and extending movement of the segments, they are moved radially by operation of a collapsing mechanism.
In general, there are two types of collapsing mechanisms in current use, one requiring a rotating actuation movement and the other requiring a reciprocating linear actuation movement. An example of a tire building drum requiring a rotating actuation movement to collapse and expand the segments is shown in U.S. Pat. Nos. 4,636,277, and 3,375,154 illustrates a tire building drum requiring a reciprocating linear actuation movement. Drive systems that provide a reciprocal actuation movement have been thought to be incompatible with tire building drums that require a rotational actuation movement, and, in some instances, this incompatibility has forced tire builders to purchase more drums and/or drive systems than would have been necessary if the drive and drum systems were capatible.
In accordance with one aspect of the present invention, a tire building machine is provided in which a drum requiring a rotational actuation movement is driven by a drive system that provides a reciprocal actuation movement. One essential element of this system is an adapter that converts reciprocal movement to rotational movement, and in accordance with one embodiment the machine comprises, in combination, a tire building drum having collapsible segments forming an outer periphery and being movable between extended and retracted positions. The tire building drum includes at least one rotatable shaft and a mechanism connects the collapsible segments to the rotatable shaft for moving the segments between the extended and retracted positions in response to rotation of the rotatable shaft. A drive mechanism is provided for rotating the drum and also includes an actuation mechanism that moves between at least first and second displaced positions. An adapter is connected between the actuation mechanism and the rotatable shaft for rotating the rotatable shaft in response to movement of the actuation mechanism between first and second displaced positions. In this manner, the collapsible segments are extended and retracted by the rotation of the rotatable shaft in response to the movement of the actuation mechanism between the first and second displaced positions.
In accordance with a further aspect of the present invention, the adapter includes a cam mechanism that converts rotating movement to reciprocating movement. For example, the adapter may include a cylindrical sleeve mounted in the adapter for rotation about the sleeve's center axis. A groove is formed in the sleeve in an orientation inclined with respect to the center axis of the sleeve, and a pin is disposed for sliding movement in the groove. In the embodiment that converts reciprocal motion to rotating motion, the pin is reciprocally driven and it rotates the sleeve to provide a rotating actuation motion for the drum. When a reciprocating actuation motion is required by a drum, the sleeve is rotatably driven which drives the pin in a reciprocating movement in the slot.